bulk rename files in directory

bulkrename.sh

#!/bin/sh

# 
# Usage: ./bulkrename.sh /backup/project dump data_backup_
#
# the files matching the pattern 
# YYYdumpXXXX will be converted to 
# YYYdata_backup_XXXX
# 
#

targetdir=$1 || "."
from=$2||'junk'
to=$3||'junk'

for file in `ls $targetdir`
do
  newname=`echo $file|sed s/$from/$to/g`
  echo "renaming from $file to $newname"
  mv $targetdir/$file $targetdir/$newname
done